Dispensing device

ABSTRACT

A device for dispensing a measured dose of liquid from an attached container which container has an elongate casing defining a dispensing cylinder, one end of the casing being adapted for mounting on the container. A plurality of dose indications are provided on the external surface of the casing so that a dose may be pre-selected by moving a dose setting collar along the casing. The collar has a stop engageable with a selected one of a multiplicity of recesses on the casing to secure the collar at the required position. A plunger having a piston co-operating with a cylinder defined by the casing is movable to lift the piston from said one end of the casing until the piston abuts the dose setting collar so charging the dispenser. Depression of the plunger to move the piston back to said one end dispenses the selected dose from an outlet port.

This application is a 371 of International PCT Application No.EP01/00860, filed Jan. 26, 2001.

This invention relates to dosing apparatus, arranged to permit thedispensing of a measured dose (volume) of a liquid from a container towhich the apparatus is connected. Though the apparatus may be used witha wide variety of liquids, it finds a particular application in thedispensing of a pharmaceutical composition.

There is a need for a dispenser able repeatedly to dispense apre-determined volume of liquid such as a pharmaceutical compositionfrom a container usually in the form of a bottle, in which the liquid isstored. Though there have been several proposals for such dispensers,these all have various disadvantages and there is no satisfactory deviceavailable commercially which adequately fulfils all requirements.

According to the present invention, there is provided dispensingapparatus for dispensing a measured dose of liquid from an attachedcontainer, which apparatus comprises: an elongate casing defining adispensing cylinder, one end of the casing being adapted for mounting ona container and the cylinder being open at the other end thereof, thecylinder being arranged to communicate with an attached container andhaving a liquid outlet port adjacent said one end; a plurality of doseindications provided on the external surface of the casing; a channelformed in the wall of the casing and extending along the length of thecylinder; a plunger having a piston co-operatively slidable within thecylinder for pumping liquid out of the attached container and throughsaid outlet port; a dose control member connected to the plunger andarranged to slide in said channel; a dose-setting collar slideable overthe external surface of the casing for alignment with a selected doseindication, the collar and dose control member being interengageable tolimit the movement of the plunger away from said one end; andrestraining means arranged between the dose-setting collar and thecasing to secure the collar with respect to the casing at a selecteddose setting.

It will be appreciated that, in use, the dose-setting collar is movedalong the casing to a position corresponding to a required dose and isthen secured at that position. Thereafter, on cycling the plunger froman initial position until its movement is blocked by the collar and thenreturning the plunger to its initial position, the required volume ofliquid is drawn into the dispensing cylinder and then ejected therefrom.

In a particularly preferred embodiment of dispenser of this invention,the casing provides a cylindrical chamber and the dispensing cylinder isdefined by a cylindrical tube mounted within the chamber at the one endof the casing, so that there is an annular clearance between theinternal wall of the casing and the external wall of the tube. Thechannel may then be formed wholly through the wall of the casing, so asto communicate with the annular clearance. The dose control member maybe a sleeve slideably mounted within the annular clearance and coupledto the plunger at the upper end thereof—that is, at the end of theplunger remote from said one end of the casing. Such as sleeve may havea first abutment which locates in the channel for sliding movementtherealong as the plunger is cycled.

Preferably, the dose-setting collar defines a second abutment which runsin the channel as the collar is moved to the required dose setting andwhich is engaged by the first abutment on sliding the plunger away fromthe one end of the casing.

The restraining means advantageously comprises a plurality of stopelements arranged along the length of the casing, the collar beingengageable with a selected stop element to be restrained againstmovement away therefrom. To increase the number of axial positions atwhich the collar may be secured with respect to the casing, such stopelements preferably are arranged helically around the casing. In apreferred embodiment, each such stop element is in the form of a recessor opening through the wall of the casing, the collar having a peg whichis engageable in a selected recess. Such a peg may be mounted on an armconnected to the collar and moveable between free and secured positions.Alternatively, the peg may be formed on a band which encircles withclearance the casing, the band being resiliently deformable to move thepeg away from the casing and so free the collar for movement along thelength of the casing.

Advantageously the dispensing apparatus is provided with a mechanismwhich is difficult for a child to operate, so as to confer a degree ofchild-resistance to the apparatus. In one embodiment, the channel has anextension into which a part of the dose control member may be received,the release of the dose control member from the extension requiring acomplex action. An alternative form provides a catch mechanism adjacentthe upper end of the plunger and which is engageable with an abutment onthe casing. In one embodiment, the release of the catch mechanismrequires a transverse force to be applied to a catch member. In another,a press-button is provided on a cap for the plunger, which button whendepressed releases the cap to permit the plunger to be drawn upwardlyand charge the dispenser with a dose. In yet another embodiment, a capfor the plunger is held to the casing by interengaging elements, untilthe cap is turned to a defined position where those elements maydisengage and permit the plunger to be drawn upwardly.

A typical bottle for containing a liquid to be dispensed by theapparatus of this invention will have a neck with external screwthreads. The one end (the lower end, in use) of the casing may beprovided with internal threads engageable with those of the neck tosecure the casing to the bottle but in alternative embodiments, the oneend of the casing is provided with resilient, inwardly directed fingerswhich are engageable behind formations on the neck of the bottle, tosecure the casing in position. Suitable profiling of the neck of thebottle and of the fingers may make it impossible to remove the casingwithout destroying one or the other of the casing or the bottle neck, soas to eliminate the likelihood of contamination of the liquid in thebottle, once opened.

By way of example only, certain specific embodiments of liquid dispenserarranged in accordance with the present invention will now be describedin detail, reference being made to the accompanying drawings, in which:

FIG. 1 is a side view of a first embodiment of liquid dispenser;

FIG. 2 is an axial section through the dispenser of FIG. 1 taken on lineA—A on that Figure;

FIG. 3 is a perspective view of the dispenser casing;

FIG. 4 is a developed view of part of the casing of FIG. 3;

FIG. 5 is a perspective view of a plunger sleeve for the dispenser;

FIG. 6 is a sectioned perspective view on the dispenser, including adip-pipe therefor;

FIG. 7 is an exploded perspective view of the components forming thedispenser of FIG. 6;

FIG. 8 shows a modified form of casing for the dispenser of FIG. 1, toprovide a child-resistant feature;

FIG. 9 shows a modified form of plunger sleeve for the dispenser of FIG.1, to provide an alternate child-resistant feature;

FIGS. 10A and 10B are sectional views on the plunger sleeve of FIG. 9,respectively in latched and released positions;

FIG. 11 is an exploded perspective view of the dispenser casing togetherwith bottle neck lock and a dip-pipe;

FIG. 12 is a sectional view through the lower end of the casing of FIG.11, when connected to a bottle;

FIG. 13 is a sectional view through an alternate form of the lower endof the casing, when connected to a bottle;

FIG. 14 is a perspective view of a second embodiment of dispenser, shownconnected to a bottle;

FIGS. 15A and 15B are vertical sections through the bottle anddispenser, respectively, of FIG. 14;

FIG. 16 is a perspective view of the casing, collar and plunger head ofthe dispenser of FIGS. 14 and 15;

FIG. 17 shows the dispenser of FIG. 16 being used to dispense a dose ofliquid;

FIGS. 18A and 18B show in more detail the collar design, respectively inreleased and locked positions;

FIG. 19 is a vertical section through an alternative casing;

FIGS. 20A and 20B show a modified form of collar, co-operating with amodified cylindrical casing and respectively in free and engagedpositions;

FIGS. 21A and 21B are isometric views of the collar of FIGS. 20A and20B, respectively free and mounted on the modified casing;

FIGS. 22A and 22B show a modified form of locking plunger head assemblyfor use with the dispenser of FIGS. 1 to 7;

FIG. 23 is an isometric view of the assembly of FIGS. 22A and 22B butwhen released; and

FIGS. 24A, 24B and 25 correspond to FIGS. 22A, 22B and 23 but of analternative locking plunger head assembly.

Referring initially to FIGS. 1 to 7, the first embodiment of dosedispenser comprises an elongate cylindrical casing 20 arranged at itslower end 21 for connection to an externally threaded neck of a bottle,in order to permit the withdrawal of a measured dose of liquid from thebottle and then to discharge that measured dose out of an outlet nozzle22. A plunger 23 is provided with an operating head 24 by means of whicha piston 25 may be drawn upwardly within a cylinder 26 mounted withinthe casing 20, so lifting liquid from the bottle and then on depressionof the operating head 24, the lifted liquid is discharged through thenozzle 22. An adjustable collar 27 is slideably mounted on the externalsurface of the casing 20, and can be locked in a required position tolimit the upward movement of the plunger 23, and so to define the volumeof the dose to be dispensed.

The cylinder 26 is formed integrally with the casing 20 and both thecylinder and the casing are open at the upper ends 29 thereof. The lowerend of the cylinder is closed by a seal member 30 having a bore 31therethrough, communicating with a spring-loaded ball check valve 32provided within a housing 33 fitted within the lower end 21 of thecasing. The ball and spring of valve 32 are retained in the housing 33by a hollow plug 28 which also seals to the member 30. A dip-pipe 34(FIGS. 6 and 7) is connected to the lower end of the housing 33 beforethe dispenser is coupled to a container, for the dispensing of liquidtherefrom.

The wall of the casing 20 is provided with a plurality of recesses 36,each extending wholly through the wall to communicate with the annularspace between the casing and the cylinder 26 therewithin. The recessesare arranged in four columns at 90° to each other, and with the recessesarranged in a helical manner, as shown in the partial developed view ofFIG. 4. A channel 37 extends parallel to the axis of the casingcentrally along one of the columns of recesses, for a purpose to bedescribed below. Between each column of recesses are provided indexnumerals which, though not shown in FIGS. 1 to 5, are shown for examplein FIGS. 14, 15 and 17B. Each recess has a corresponding index numeralassociated with it, though not necessarily immediately adjacent it. Inan alternative design, the recesses 36 could extend only part waythrough the wall of casing 20.

The plunger 23 includes a piston rod 39 of cruciform section, with thehead 24 mounted on the upper end thereof. The piston 25 comprises aresilient washer fitted to the lower end of the rod and is a sliding andsealing fit within the cylinder 26. A plunger sleeve 40 is a sliding fitin the annular space between the cylinder 26 and the casing 20, thesleeve having an inwardly turned flange 41 at its upper end. The sleeve40 is mounted on the piston rod 39 by means of the flange 41, which isreceived in a recess beneath the head 24, to secure the sleeve againstmovement with respect to the rod. At the lower end of the sleeve 40,there is an outwardly projecting peg 42, which is a sliding fit withinthe channel 37. This restrains rotation of both the sleeve and the rod23. As best seen in FIG. 5, a column of serrations 43 is aligned withthe peg 42.

The collar 27 has annular first and second parts 44 and 45 coupledtogether in such a way that they may rotate relatively but slide inunison along the length of the casing 20. The first part 44 has a window46 which may be aligned with any selected index numeral on the casing sothat the whole of the index numeral may be viewed through the window.When in such a position, a stop 47 provided on a hinged arm 48 may bepressed into a corresponding recess 36, the arm then snapping behind acatch therefor, to retain the arm in the closed position. The edges ofthe stop 47 are bevelled so as to assist the entry of the stop into aselected recess and accurately to position the collar with respect tothe selected recess, when fully home.

The second part 45 of the collar has an abutment 49 (FIG. 7) located inthe channel 37 for sliding movement therealong, as the first part 44 ismoved axially to have a selected index numeral positioned within thewindow 46. The inwardly directed face of the abutment 49 is serrated andengages the serrations 43 on the plunger sleeve 40, so as to resistaxial movement of the plunger sleeve, and so also the plunger, until asufficient force has been applied to the plunger.

A port 51 (FIG. 6) is formed through the casing at the lower end of thecylinder 26 and communicates with the nozzle 22. A spring-loaded ballcheck valve 52 is provided within the nozzle and downstream of the valveis an outlet spout 53.

FIG. 8 shows a modification of the casing 20, to confer a degree ofchild-resistance to the dispenser. The channel 37 is provided with anextension 54 at its lower end, which extends in the circumferentialdirection and is provided with a receptor 55 for the peg 42 on theplunger sleeve 40. The peg may be located in the receptor by pressingdownwardly on the plunger head 24; the downward pressure causes the peg42 to ride on the angled bottom wall of the channel 37 to guide the peginto the receptor 55, with a snap action. Conversely, to release the pegfrom the receptor, the head must be pulled upwardly and simultaneouslytwisted in a counter-clockwise direction (when viewed from above) inorder to set the dispenser ready for dispensing a selected dose.

FIGS. 9, 10A and 10B show an alternative arrangement for conferring adegree of child-resistance. Here, a slider 56 is mounted at the upperend of the piston rod 39, between the sleeve 40 and plunger head 24, forsliding movement transversely of the plunger. The slider includes a pairof spring arms 57 which engage lands on the cruciform piston rod 39 andurge the slider to the right, in FIGS. 9 and 10. The slider includes ahook member 58 which depends downwardly from one side and on theopposite side is an operating surface 59 which effectively forms a partof the plunger head 24. An outwardly directed lip 60 is formed at theupper end 29 of the casing and extends partway therearound, on theopposite side to the channel 37.

Depression of the plunger 23 with an increased force from its normalbase position will snap the hook member 58 over the lip 60, to engagetherebehind and so lock the plunger, as shown in FIG. 10A. To releasethe plunger, the operating surface 59 must be pressed against the springbias provided by the arms 57, so moving the hook member 58 clear of thelip 60, as shown in FIG. 10B.

The lower end 21 of the casing 20 shown in FIG. 2 is internallythreaded, for interengagement with the conventional external threads ona bottle neck and which otherwise would receive a cap or other closure.FIGS. 11 to 13 show alternative arrangements in order to facilitate theattachment of the casing to an externally threaded bottle neck, merelyby pressing the casing down on to the neck and obviating the need tomake a threaded connection.

In the arrangement of FIG. 12, the lower end of the casing is formed asa bell housing 62 having four apertures 63 formed therethrough. A stiffbut resilient locking member 64 is fitted into the bell housing 62 andhas lugs 65 which engage in the aperture 63. The locking member 64 has aplurality of upwardly and inwardly projecting fingers 66, which areadapted to engage behind a bead 67 formed at the free end of the bottleneck 68. The lower part of the locking member 64 fits against a lowerbead 69 below the threads on the neck, and the housing 33 for the checkvalve 32 is a close fit within the neck of the bottle. The upper end ofthe neck engages an outwardly projecting flange 70 to effect a sealthereagainst, when the fingers fully engage behind the bead 67. In thisway, the dispenser is stably mounted on the neck of the bottle eventhough it is not tightened down using the external threads.

FIG. 13 shows an alternative design to that shown in FIG. 12 but likeparts are given like reference numerals. Here, the apertures 63 areformed towards the upper end of the bell housing 62 and a locking member71 has fingers 66 projecting inwardly and upwardly from the lower end ofthe locking member, to engage behind the lower bead 69 of the bottleneck. Internally, the upper end of the bell housing 62 has a smallerdiameter directly to engage the threads on the bottle neck and so toassist in stably mounting the casing on the bottle.

In use, the casing is fitted to a bottle of liquid either by screwingthe threads at the lower end of the casing on to the external threads onthe bottle neck (for the arrangement of FIG. 2) or merely by pressingthe casing on to the bottle neck (for the arrangements of FIGS. 12 and13). The collar 27 is set so that the required dose is visible throughthe window 46 and the collar is then locked in position by pressing thehinged arm 48 inwardly to engage the stop 47 thereof in thecorresponding recess 36. After releasing the child resistant lock (ifprovided), the plunger is pulled upwardly to fill the space beneath thepiston with liquid, which passes through the check valve 32 while checkvalve 52 prevents the ingress of air into the cylinder. Upward movementof the plunger is limited by the peg 42 on the plunger sleeve 40engaging the underside of the abutment 49 on the second part of thecollar, locked at the required dose setting. Thereafter, the plungerhead 24 is pressed downwardly, to discharge the dose through the secondcheck valve 52, the nozzle 22 and spout 53. The first check valve 32resists the return of liquid into the bottle.

FIGS. 14 to 17 show a second embodiment of dispenser which is generallysimilar to that described above primarily with reference to FIGS. 1 to5, and will not be described again in detail. This second embodimentdiffers in that no side port leading to a radial outlet nozzle 22 isprovided; rather, a single port 72 (FIG. 15B) is formed internallywithin the lower end of the casing 20, so that a charge of liquid drawninto the cylinder 26 may be dispensed downwardly through that port oncethe casing has been released from a bottle, as shown in FIGS. 16 and 17.

As shown in FIG. 15A, the bottle 73 is provided with a dip pipe 74having a flange 75 at its upper end and which is snap-fitted to thebottle 73, in an essentially permanent manner. At its lower, the dippipe includes a spring-loaded one-way diaphragm valve 76 permittingliquid to enter the dip pipe from the bottle but preventing the returnof liquid to the bottle from the pipe. Prior to the connection of thedispenser (FIG. 15B) to the bottle (FIG. 15A), the bottle is closed by acap 77.

The dispenser is generally similar to that described above but differsin that no valve is provided at its lower end 78. That lower end 78 isformed to fit over flange 75 in a sealing manner and has a singlecentral nozzle 79 engageable in the upper end of the dip pipe 74. To usethis dispenser, the casing is connected to the bottle and the requiredvolume is drawn into the cylinder 26 following the setting of therequired dose on collar 27. The dispenser is then removed from thebottle and the liquid drawn from the bottle is dispensed into a tumbleror cup by depressing the head 24 of the plunger, as shown in FIG. 17.

The collar 27 of this embodiment is of a slightly different form, withthe window 46 formed in a recess 80 extending axially of the collar forthe full height thereof, and with arm 48 hinged in a similar recess 81on the opposite side of the collar (FIG. 16). The recess for the arm 48has a lip along the edge wall 82 remote from the hinged connection ofthe arm, so that the free end of the arm may snap behind the lip to holdthe arm in its closed position and with its stop engaged in a recess forthe selected dose.

FIGS. 18A and 18B are enlarged views of the collar design shown fromexample in FIGS. 1, 2 and 7. As can be seen, the collar 27 issubstantially cylindrical, with the window 46 formed through the wholethickness of the collar. The arm 48 is hinged within a circumferentiallyelongate recess 83, also formed through the whole thickness of thecollar. The walls defining the stop 84 taper towards the free end of thestop to facilitate entry of the stop into a selected recess. A groove 85is provided along the junction between the lower wall 86 of the recessand the arm 48 which groove snaps behind the inner wall of the collar asthe arm 48 is closed fully, so resisting subsequent opening movement ofthe arm.

In FIG. 19, there is shown an alternative casing design which isgenerally similar to that of FIGS. 1, 2 and 6 and like parts are againgiven like reference characters; those parts will not be described againhere. The lower end of the casing 20 has an integrally formed valvehousing 87, into which a one-way ball valve assembly 88 is fitted fromwithin the cylinder 26 and is secured in position by a hollow plug 89.The lower end of the housing 87 is arranged to receive a dip pipe 34, aswith the previous embodiments. Also, the upper end 29 of the cylinder 26is slightly flared, so as to give a lead-in for the piston of theplunger (not shown in FIG. 19).

The lower end of the casing is adapted to accommodate a locking membersuch as that shown in FIG. 12, for one-time use on a bottle not having athreaded neck. In other respects, this arrangement corresponds to thosedescribed above and is used in essentially the same manner.

Turning now to FIGS. 20 and 21, there is shown an adjustable collar 91to replace collar 27 described above. This collar 91 has a ring 92 ofgenerally cylindrical form and defining a window 93 for reading markingson casing 20. A band 94 has its two ends connected to the part of thering 92 defining the window 93, to encircle with clearance the casing20. Externally, the band 94 is provided with two finger buttons 95disposed approximately at 90° to the window 93. Internally, andgenerally opposite the window, the band has a pair ofcircumferentially-spaced inwardly-projecting abutments 96. The abutmentsare in adjacent radial planes to permit simultaneous interengagementwith two recesses respectively, formed on the casing 20.

The collar 91 is moulded from a resilient plastics material, so thatwhen in its relaxed condition, the band 94 takes up a generally circularconfiguration as shown in FIG. 20B, with the abutments engaged in twoadjacent recesses 36 of casing 20. Squeezing together the opposedbuttons 95 causes the band 94 to deform as shown in FIG. 20A, moving theabutments 96 radially away from the casing and so freeing the collar 91to slide axially along the casing to a chosen position. When theappropriate setting can be read through window 93, releasing the buttons95 allows the abutments to engage the appropriate recesses, though itmay be necessary to make a minor adjustment to the axial position of thecollar, to achieve this.

In order to enhance the clarity of the markings visible through thewindow 93, the casing 20 may be provided with a series ofaxially-extending flats on which the markings are provided. Such flatsare shown at 97 in FIG. 21B.

In other respects, the adjustable collar 91 functions as has beendescribed above in relation to adjustable collar 27; collar 91 will nottherefore be described in further detail here.

FIGS. 22 and 23, and FIGS. 23 and 24 respectively show two locking headassemblies for use with the plunger 23 of the embodiment described withreference to FIGS. 1 to 7. Each of these will now be described.

In the assembly of FIGS. 22A, 22B and 23, the plunger 23 is fitted atits upper end with a cap 101 having a top plate 102 connected to theplunger by stud 103, the cap having a depending skirt 104. Twodiametrically opposed, inwardly-directed hook-shaped tabs 105 areprovided on the lower edge of the skirt 104. The upper end 29 of thecasing 20 is furnished with a collar 106 having a rim 107 at its lowerend, the upper surface of the rim being bevelled as shown in thedrawings. Four spring blades 108 project upwardly from the upper part ofthe collar 106, for engagement by the internal surface of the top plate102 of the cap.

The rim 107 has a pair of channels 109 therethrough, a shaped guard wall110 being provided on the collar above each channel and first and secondstops 111 and 112 projecting downwardly from the rim, on both sides ofeach channel, respectively. The tabs 105 may pass through the channels109 when appropriately aligned therewith but otherwise are normallydisposed below the rim 107, as shown in FIG. 22B. The plunger is thusheld in its fully depressed position by interengagement of the tabs 105with the rim 107, the spring blades 108 serving to maintain the tabsengaged with the rim. In addition, the spring blades resist rotation ofthe cap 101 in a counter-clockwise direction, when viewed from above.

When a dose is to be dispensed, the cap 101 is turned clockwise untilthe tabs 105 engage the respective smaller first stops 111. The cap isthen depressed against the action of the spring blades to ride the tabsover the stops 111 until the tabs engage the larger second stops 112;each tab is then aligned with and may enter the respective channel 109.Lifting the cap slightly engages the tabs with the walls 110, so causingthe cap to turn a little further in the clockwise direction. From here,the dispenser may be primed with the pre-set dose, defined by theadjustable collar 27 (or 91) as has been described hereinbefore.

The dose is dispensed by pressing down on the cap 101 to drive theplunger to the bottom of its stroke. As this point is reached, the tabs105 ride over the bevelled rim 107, to re-engage therebehind, making anaudible click at the same time, to inform a user that the full dose hasbeen dispensed. The walls 110 ensure that the tabs 105 will not bealigned with the channels 109 at the completion of the stroke, soensuring that the releasing action described above must be performednext time a dose is to be dispensed.

In the assembly of FIGS. 24A, 24B and 25, the plunger 23 is fitted atits upper end with a cap 115 having a resilient central press-button116. That press-button has a pair of opposed legs 117 dependingdownwardly through corresponding slots in the cap, each leg terminatingin a barb 118. The legs 117 are partially covered and protected by meansof a pair of opposed tabs 119 formed on the cap 115.

A collar 120 is furnished on the upper end of the casing 20, whichcollar has an outwardly-directed rim 121, behind which the barbs 118engage, when the plunger is at the bottom of its stroke, as shown inFIG. 24A. Depression of the press-button 116 causes the legs 117 to moveoutwardly, as shown in FIG. 24B, so freeing the barbs 118 from the rim121 and allowing the plunger to be drawn upwardly, to charge thedispenser with a dose to be dispensed. In view of the resilience of thepress-button 116, release of it allows the legs 117 to return to theposition shown in FIG. 24A ready to catch the barbs behind the rim 121again.

The two plunger head assemblies of FIGS. 22 to 25 confer on thedispenser considerable child-resistant properties and so assist inpreventing unauthorised use, by a minor, of the dispenser.

What is claimed is:
 1. A dispensing apparatus for dispensing a measureddose of liquid from an attached container, which apparatus comprises: anelongate cylindrical casing, one end of said cylindrical casing beingadapted for mounting on a container, said cylindrical casing being openat the other end thereof, said cylindrical casing being arranged tocommunicate with an attached container, said cylindrical casing having aliquid outlet port adjacent said one end, said cylindrical casing havingan outwardly directed lip; a plurality of dose indications provided onthe external surface of said cylindrical casing; said cylindrical casinghaving a channel formed in a wall therein, said channel extending alongthe length of said cylindrical casing; a plunger, said plunger having apiston with a rod attached thereto being co-operatively slidable withinsaid cylindrical casing for pumping liquid out of the attached containerand through said outlet port; a dose control member, said dose controlmember being connected to the plunger, the dose control member arrangedto slide in said channel; a dose-setting collar, said dose-settingcollar being slidable over the external surface of said cylindricalcasing for alignment with a selected dose indication, said dose-settingcollar and dose control member being interengageable to limit themovement of the plunger away from said one end; restraining means, saidrestraining means being arranged between said dose-setting collar andsaid cylindrical casing, wherein said restraining means comprises aplurality of stop elements, said stop elements being arranged along thelength of said cylindrical casing, said dose-setting collar beingengageable with a selected stop element thereby being restrained againstmovement away therefrom; and a slider, said slider having a hook member,said hook member engageable with said outwardly directed lip on saidcylindrical casing, said slider having at least one spring arm, saidspring arm being engageable with said piston rod.
 2. The dispensingapparatus of claim 1, wherein said cylindrical casing provides acylindrical chamber, said cylindrical chamber being defined by acylindrical tube mounted at said one end of said cylindrical casing,said cylindrical casing and said cylindrical chamber having an annularclearance defined therebetween.
 3. The dispensing apparatus of claim 2,wherein said channel communicates with said annular clearance.
 4. Thedispensing apparatus of claim 3, wherein said dose control membercomprises a sleeve slideably mounted within said annular clearance. 5.The dispensing apparatus of claim 4, wherein said dose control memberhas a first abutment which is slideably disposed within said channel. 6.The dispensing apparatus of claim 5, wherein said dose-setting collardefines a second abutment which runs in said channel and which isengaged by said first abutment of said dose control member when saidplunger slides away from said one end.
 7. The dispensing apparatus ofclaim 1, wherein said stop elements are disposed both along the lengthof said cylindrical casing and around the periphery thereof, in anhelical array.
 8. The dispensing apparatus of claim 7, wherein said doseindications comprise index marks, there being a unique index mark foreach selectable dose and being associated with a corresponding stopelement.
 9. The dispensing apparatus of claim 8, wherein each of saidstop elements is in the form of a recess in said cylindrical casing, andwherein said dose-setting collar has a peg engageable in selectedrecess.
 10. The dispensing apparatus of claim 9, wherein said peg ismounted on an arm connected to said dose-setting collar, which arm ismovable between a peg-engaged position and a peg-free position.
 11. Thedispensing apparatus of claim 9, wherein said peg is mounted on a bandwhich surrounds said cylindrical casing, which band is resilientlydeformable in order to move said peg into and out of engagement with theselected recess in said cylindrical casing.
 12. The dispensing apparatusof claim 11, wherein said dose-setting collar is provided with a windowthrough which a selected dose index mark may be observed when saiddose-setting collar is engaged with the corresponding dose stop element.13. The dispensing apparatus of claim 1, wherein releasable catch meansis provided for said plunger, whereby said releasable catch meansrestrains the plunger at a base position with said piston adjacent tosaid one end of said cylindrical casing, until said releasable catchmeans is released.
 14. The dispensing apparatus of claim 13, whereinsaid releasable catch means comprises an extension to said channel andwhich has a portion extending in the circumferential direction of saidcylindrical casing, and wherein said dose control member is receivablein and removable from said extension by relative rotational movementwith respect to said cylindrical casing.
 15. The dispensing apparatus ofclaim 14, wherein said extension to said channel includes a step behindwhich said dose control member may be located.
 16. The dispensingapparatus of claim 13, wherein said releasable catch means has a catchmember mounted on said plunger, said catch member being engageable withan abutment at said other end of said cylindrical casing.
 17. Thedispensing apparatus of claim 16, wherein said catch member is definedby a cap having an inwardly-directed tab, said other end of saidcylindrical casing being provided with a tab collar having anoutwardly-projecting rim, behind which said inwardly-directed tab isengageable.
 18. The dispensing apparatus of claim 17, wherein saidoutwardly-projecting rim of said inwardly-directed tab has a tab channelformed there-through, whereby said plunger may be moved away from saidone end of said cylindrical casing only when said tab is aligned withsaid tab channel.
 19. The dispensing apparatus of claim 16, wherein saidplunger is provided with a button cap, said button cap having aresilient press-button which, when depressed, moves said catch memberradially outward and out of engagement with said abutment at said otherend of said cylindrical casing.
 20. The dispensing apparatus of claim 1,wherein said one end of said cylindrical casing is provided with acontainer recess within which a neck portion of a container may bereceived, said container recess being provided with engagement means inorder to engage externally-formed threads on the neck portion of thecontainer.
 21. The dispensing apparatus of claim 20, wherein saidengagement means comprises a plurality of inwardly-directed resilientfingers, said plurality of inwardly-directed resilient fingers havingfree ends which are engageable with at least one external rib on thecontainer neck, whereby said cylindrical casing may be mounted on thecontainer neck by pressing said cylindrical casing on to the containerneck.
 22. The dispensing apparatus of claim 1, wherein a dip-pipe isprovided at said one end of said cylindrical casing in order tocommunicate with liquid in an attached container, said dip-pipe havingan associated one-way valve in order to prevent flow of liquid out ofsaid cylindrical casing, said dip-pipe having a free end.
 23. Thedispensing apparatus of claim 22, wherein said one-way valve is providedat said one end of said cylindrical casing, said cylindrical casingfurther having an other one-way valve being associated with said liquidoutlet port.
 24. The dispensing apparatus of claim 22, wherein saidone-way valve is provided at said free end of said dip-pipe wherein saidone way valve is remote from said cylindrical casing.